Pressure-sensitive adhesives for bonding flexible printing plates

Abstract

Pressure-sensitive adhesives and methods, for bonding flexible printing plates, comprising at least one adhesive component comprising at least one polymer component based on a monomer mixture comprising at least one of the following monomers: at least one acrylic ester; at least one methacrylic ester; acrylic acid; and methacrylic acid. The pressure-sensitive adhesives further comprise 1 to 30 wt %, based on the overall blend of the at least one adhesive component without solvent, of a polyvinyl acetate.

The invention claimed is: 
     
       1. A method comprising:
 bonding of one or more printing plates to at least one selected from one or more printing cylinders and one or more printing sleeves with a pressure-sensitive adhesive comprising at least one adhesive component comprising at least one polymer component based on a monomer mixture comprising at least one of the following monomers: 
 at least one acrylic ester; 
 at least one methacrylic ester; 
 acrylic acid; and 
 methacrylic acid, 
 wherein the pressure-sensitive adhesive further comprises 
 10 to 25 wt %, based on the overall blend of the at least one adhesive component without solvent, of a polyvinyl acetate. 
 
     
     
       2. The method according to  claim 1 , wherein the polyvinyl acetate has a molar mass M n  of 10,000 to 100,000 g/mol. 
     
     
       3. The method according to  claim 2 , wherein the polyvinyl acetate has a molar mass M n  of 15,000 to 25,000 g/mol. 
     
     
       4. The method according to  claim 1 , wherein the monomer mixture comprises at least the following monomers:
 a) 20 to 99.5 wt % of at least one first acrylic ester and/or methacrylic ester whose homopolymer has a static glass transition temperature of <0° C.; 
 b) 0 to 40 wt % of at least one second acrylic ester and/or methacrylic ester whose homopolymer has a static glass transition temperature of >0° C.; 
 c) 0.5 to 20 wt % of acrylic acid and/or methacrylic acid; and 
 d) 0 to 25 wt % of further copolymerizable monomers, the quantity figures being based in each case on the monomer mixture. 
 
     
     
       5. The method according to  claim 4 , wherein the at least one first acrylic ester and/or methacrylic ester whose homopolymer has a static glass transition temperature of <−20° C. and the at least one second acrylic ester and/or methacrylic ester whose homopolymer has a static glass transition temperature of >20° C. 
     
     
       6. The method according to  claim 1 , wherein the monomer mixture comprises at least the following monomers:
 i.a) 50-99.5 wt % of at least one acrylic ester and/or methacrylic ester having the following formula:
   CH 2 ═C(R 1 )(COOR 2 ), where
 
 R 1 =H and R 2  is a linear alkyl radical having 2 to 10 carbon atoms or is a branched, non-cyclic alkyl radical having at least 4 carbon atoms, and/or 
 R 1 =CH 3  and R 2  is a linear alkyl radical having 8 to 10 carbon atoms or is a branched, non-cyclic alkyl radical having at least 10 carbon atoms; 
 
 i.b) 0 to 40 wt % of at least one acrylic ester and/or methacrylic ester having the following formula:
   CH 2 ═C(R 3 )(COOR 4 ), where
 
 R 3 =H or CH 3  and R 4  is a linear alkyl radical having at least 12 carbon atoms, preferably a stearyl radical; 
 
 i.c) 0.5-20 wt % of acrylic acid and/or methacrylic acid; and 
 i.d) 0-25 wt % of at least one N-alkyl-substituted acrylamide, where the quantity figures are based in each case on the monomer mixture. 
 
     
     
       7. The method according to  claim 1 , wherein the monomer mixture comprises at least the following monomers:
 ii.a) 49.5-89.5 wt % of at least one acrylic ester and/or methacrylic ester and/or their free acids, having the following formula:
   CH 2 ═C(R 5 )(COOR 6 ), where
 
 R 5 =H or CH 3  and R 6  is an alkyl radical having 1 to 10 carbon atoms or H and the homopolymer has a static glass transition temperature of <−30° C.; 
 
 ii.b) 10 to 40 wt % of at least one acrylic ester and/or methacrylic ester having the following formula:
   CH 2 ═C(R 7 )(COOR 8 ), where
 
 R 7 =H or CH 3  and R 8  is a cyclic alkyl radical having at least 8 carbon atoms or is a linear alkyl radical having at least 12 carbon atoms and the homopolymer has a static glass transition temperature T g  of at least 30° C.; and 
 
 ii.c) 0.5 to 10 wt % of at least one acrylic ester and/or methacrylic ester and/or their free acids, having the following formula:
   CH 2 ═C(R 9 )(COOR 10 ), where
 
 R 9 =H or CH 3  and R 10 =H or an aliphatic radical having a functional group X, 
 where X comprises COOH, OH, SH, SO 3 H, and the homopolymer has a static glass transition temperature T g  of at least 30° C., where R 11 =H or a linear or branched alkyl radical having up to 10 carbon atoms, 
 
 wherein the quantity figures are based in each case on the monomer mixture. 
 
     
     
       8. The method according to  claim 1 , wherein the monomer mixture comprises at least the following monomers:
 iii.a) 25 to 82 wt % of linear acrylic esters having 2 to 10 carbon atoms in the alkyl radical; 
 iii.b) 0 to 40 wt % of branched, non-cyclic acrylic esters having a static glass transition temperature T g  of not more than 0° C., preferably not more than −10° C., more particularly not more than −20° C.; 
 iii.c) 8 to 15 wt % of acrylic acid, based on the total amount of monomers to be polymerized; and 
 iii.d) optionally up to 10 wt % of further copolymerizable monomers, based on the total amount of monomers to be polymerized, 
 wherein the ratio of the linear acrylic esters to the branched acrylic esters is in the range from 1:6 to 10:1 mass fractions. 
 
     
     
       9. The method according to  claim 4 , wherein the polymer component or polymer components based on monomer mixtures comprising the monomers a) to d) make(s) up at least 90 wt % of the adhesive component or components. 
     
     
       10. The method according to  claim 9 , wherein the polymer component or polymer components based on monomer mixtures comprising the monomers a) to d) make(s) up at least 99.9 wt % of the adhesive component or components. 
     
     
       11. The method according to  claim 1 , wherein the pressure-sensitive adhesive is in crosslinked form. 
     
     
       12. The method according to  claim 1 , wherein the pressure-sensitive adhesive is provided in the form of an adhesive tape. 
     
     
       13. The method according to  claim 1 , wherein the pressure-sensitive adhesive further comprises 10 to 20 wt %, based on the overall blend of the at least one adhesive component without solvent, of the polyvinyl acetate. 
     
     
       14. The method according to  claim 13 , wherein the pressure-sensitive adhesive further comprises 10 to 15 wt %, based on the overall blend of the at least one adhesive component without solvent, of the polyvinyl acetate.